Generally, a gas-insulated switchgear device comprises a circuit breaker having a grounded hermetic-vessel in which an electrically insulating gas such as an SF6 gas is filled, and a high voltage live part insulatedly disposed in the hermetic vessel, a disconnecting switch, a bus line, and the like. Since the gas-insulated switchgear devices are safe and highly reliable, and installation areas of the gas-insulated switchgear devices can be considerably reduced, in recent years, the gas-insulated switchgear devices have been used in various locations. Incidentally, a gas-insulated switchgear device of a 3/2 circuit breaker system has been employed in an important system.
A diameter is constructed by causing three circuit breakers, to both ends of which disconnecting switches are connected, to be connected between a pair of main bus lines, causing a rectifier, an earth switch and the like to be connected between the main bus lines, causing branch bus lines to be connected between the disconnecting switches, and causing end portions of the branch bus lines to be insulatedly led out by cable heads or bushings. Another diameter is also provided between the main bus lines. In the first diameter, the branch bus lines are led out toward the main bus lines or the branch bus lines are lead out toward the main bus lines. On the other hand, in the second diameter, the branch bus lines are led out toward the main bus lines or the branch bus lines are lead out toward the main bus lines. Thus, load balance is maintained.
The gas-insulated switchgear device is disclosed in Japanese Patent Application Laid-open No. Hei. 11-355923. In this gas-insulated switchgear device, main bus lines are spaced a predetermined distance apart from each other and disposed in substantially parallel to each other, three circuit breakers having disconnecting switches at both ends thereof are disposed in a direction bridging the main bus lines, and branch bus lines are connected between the disconnecting switches connected to the both ends of the circuit breakers. The branch bus lines are led out in a same direction, together with a diameter, so that there is a problem of concentration of load of the branch bus lines.
Moreover, Japanese Patent Application Laid-Open No. Hei. 11-355923 also discloses a gas-insulated switchgear device in which branch bus lines in one of diameters are led out in a direction opposite to each other and branch bus lines in the other of the diameters are led out in such direction as to cross.
However, when the gas-insulated switchgear device has the diameter in which the branch bus lines are led out in such directions as to cross, and the three circuit breakers are disposed in the direction bridging the pair of the main bus lines, so that a large installation area for the gas-insulated switchgear device is required in the direction bridging the main bus lines. In addition, the branch bus lines are disposed between the diameters, so that a large installation area is also required in axial directions of the main bus lines.
Moreover, in the conventional gas-insulated switchgear device, it is not taken into consideration that dismantlement and inspection work of the circuit breakers will be carried out at the time of the occurrence of accidents of the circuit breakers. If a work space for facilitating the dismantlement and inspection work of the circuit breakers is provided in the gas-insulated switchgear device, the gas-insulated switchgear device inevitably becomes a gas-insulated switchgear device having a large installation area. Therefore, it is feared that carrying-out of circuit breakers required to be dismantled and repaired must be performed by dismantling the main bus lines and then lifting up the main bus lines.
The present invention has been made with a view to overcoming the foregoing problems of the prior art gas-insulated switchgear device. It is therefore an object of the present invention to provide a gas-insulated switch gear device in which a space for dismantlement and inspection work which facilitates the dismantlement and inspection work of circuit breakers at the time of the occurrence of accidents of the circuit breakers can be sufficiently obtained and an installation area for the gas-insulated switchgear device can be reduced.